A fiery explosion for 40 points of damage in a 15 foot radius. Targets on fire take extra damage.
Fireball is an adept level Destruction spell that deals fire damage over an area upon projectile impact and sets targets on fire for 30% of immediate spell damage, scaling down quadratically over 2 seconds.
Fireball will damage friends as well as foes in its area of effect (though it will not damage the caster). With this in mind, use this spell carefully if you have followers who fight melee. Even Protected NPCs (though not Essential ones) can be killed in this manner.
Like most Fire spells, it can be used to set off Fire Runes or Oil Slicks from a safe distance. Also, casting it or merely having it ready to cast in an area with Flammable Gas will result in a massive explosion.
It is suggested that you aim for the target's feet rather than their body. This decreases their chances of avoiding damage if you miss.